Method, Device, and System for Traffic Switching in Multi-Protocol Label Switching Traffic Engineering

1. A method for maintaining an active Label Switching Path (LSP) upon temporarily switching to a standby LSP by utilizing Bidirectional Forwarding Detection (BFD) in a Multi-Protocol Label Switching (MPLS) network, in which data traffic is transmitted based on MPLS forwarding entries, the MPLS forwarding entries are created on a control plane of a router in the MPLS network and delivered to a forwarding plane of the router; the method comprising: transmitting upstream data traffic over the active LSP based on MPLS forwarding entries of routers locating on the active LSP; upon detecting a fault of the active LSP, switching the upstream data traffic to the standby LSP; transmitting the upstream data traffic over the standby LSP based on MPLS forwarding entries of routers locating on the standby LSP; creating a BFD session on forwarding planes of the routers locating on the active LSP to detect a current state of the active LSP; after the fault of the active LSP is rectified, utilizing the BFD session for detecting that whether forwarding entries created on control planes of the routers locating on the active LSP are delivered completely to the forwarding planes of the routers locating on the active LSP; and if the forwarding entries created on the control planes of the routers locating on the active LSP are delivered completely to the forwarding planes of the routers locating on the active LSP, switching the upstream data traffic back to the active LSP.

2. The method of claim 1 , wherein before detecting that the forwarding entry on the active LSP is delivered completely, the method further comprises: setting a state of the active LSP on a forwarding plane to be unavailable.

3. The method of claim 1 , wherein before switching the traffic back to the active LSP, the method further comprises: setting the state of the active LSP on the forwarding plane to be available.

4. A network node device, comprising: a forwarding unit, configured to detect a state of delivering a forwarding entry on an active Label Switching Path (LSP), after a fault of the active LSP is rectified, utilize a Bidirectional Forwarding Detection (BFD) session for detecting that whether forwarding entries created on control planes of routers locating on the active LSP are delivered completely to forwarding planes of the routers locating on the active LSP, and switch traffic back to the active LSP if determining that the forwarding entry on the active LSP is delivered completely.

5. The device of claim 4 , further comprising: a receiving unit, configured to receive traffic and a Bidirectional Forwarding Detection (BFD) feedback message and send the traffic and the BFD feedback message to the forwarding unit.

6. The device of claim 5 , further comprising: a controlling unit, configured to generate the forwarding entry, and deliver the forwarding entry, where information indicating that the active LSP is unavailable is carried, to the forwarding unit.

7. The device of claim 6 , wherein the forwarding unit comprises: a receiving module, configured to receive the traffic and the BFD feedback message, and send the traffic and the BFD feedback message to a processing module; receive the forwarding entry sent by the controlling unit, and send the forwarding entry to a storing module; and receive the information indicating that the active LSP is unavailable sent by the controlling unit, and send the information indicating that the active LSP is unavailable to an Active-LSP-state changing module; a binding module, configured to bind BFD, generate a BFD message which is used for checking a state of the active LSP and send the BFD message to a sending module; the storing module, configured to receive the forwarding entry sent by the receiving module and store the forwarding entry; the processing module, configured to receive the BFD feedback message; and, if an information about completion of delivering the forwarding entry is carried, send an information indicating that the active LSP is available to the Active-LSP-state changing module, and switch back the traffic; receive the traffic sent by the receiving module, query a corresponding forwarding entry from the storing module, and send the traffic to the sending module; the Active-LSP-state changing module, configured to receive the information indicating that the active LSP is unavailable sent by the receiving module, and set the state of the active LSP to be unavailable; and receive the information indicating that the active LSP is available from the processing module, and set the state of the active LSP to be available; and the sending module, configured to receive the BFD message sent by the binding module and the traffic sent by the processing module, and send them out.

8. A system for traffic switching in Multi-Protocol Label Switching Traffic Engineering (MPLS TE), comprising: a first provider edge router (PE 1 ) configured to detect a state of an active Label Switching Path (LSP), check whether forwarding entry on the active LSP is delivered completely, and switch traffic back to the active LSP so that the traffic is transmitted over the active LSP; a second provider edge router (PE 2 ) configured to recover the active LSP with the PE 1 by using signaling of a control plane of the PE 1 after the active LSP is faulty; a first provider router (P 1 ) configured to transmit the traffic through a standby LSP when the active LSP is faulty; a second provider router (P 2 ) configured to set up the active LSP again by using the signaling of the control plane of the PE 1 after the active LSP is faulty, and detect the state of the active LSP; wherein the active LSP is between the PE 1 and the PE 2 through the P 2 , and the standby LSP is between the PE 1 and the PE 2 through the P 1 .

9. The system of claim 8 , wherein: the PE 1 comprises a means for configuring a Bidirectional Forwarding Detection (BFD) binding relationship, create a BFD session over the active LSP on a forwarding plane, and detect the state of the active LSP by using the BFD session.

10. The system of claim 9 , wherein: the P 2 comprises a means for receiving the BFD session sent by the forwarding plane of the PE 1 , and send the BFD session to the PE 2 .